Various types of window assemblies exist including a pivotable window sash assembly which includes a tilt window sash mounted to a channeled window frame. In use, the window sash would move up and down and would also be capable of pivoting outwardly with respect to the window frame for access, for example, in cleaning the window. A conventional mechanism for accomplishing these movements is to include a balance shoe which is mounted for slidable movement in a channel in the window frame. A pivot bar is secured to the window sash and is engaged with the balance shoe. In this manner the balance shoe moves in the channel which acts as a track during the up and down movement of the window sash. In one form of balance shoe a freely mounted sleeve is included in the balance shoe with a slot in the sleeve engaged by an arm on the pivot bar. As a result, it is possible to rotate the window sash because of the pivotal connection effected by the sleeve being able to freely pivot within its balance shoe.
U.S. Pat. Nos. 4,930,254, 5,069,001 and 5,237,775 reflect various prior art approaches for mounting a pivot bar to a balance shoe and various details of pivotable window sash assemblies.